Document FR-2,720,113 notably discloses an indirect-injection internal-combustion engine with one cylinder and two intake manifolds opening each into the combustion chamber and associated with shutoff means such as a valve for communicating each manifold with the combustion chamber. Each manifold is equipped with at least one fuel injection means such as an injection nozzle allowing fuel to be fed into the manifold and thus a fuel mixture to be obtained at the outlet of this manifold.
In this type of engine, a fuel mixture is formed upstream from the combustion chamber in at least one pipe so as to meet the running conditions of the engine. More precisely, at low loads, one of the manifolds is closed whereas the other remains open by injecting therein fuel in sufficient amount to obtain a homogeneous fuel mixture with a fuel/air ratio close to 1, then this mixture is fed into the combustion chamber. For average loads, the two manifolds are open and one of the manifolds is supplied with fuel so as to obtain a fuel mixture having a fuel/air ratio of substantially 1, whereas the fuel is not fed into the other manifold. This allows to have a stratification between the fuel mixture with a fuel/air ratio of 1 and the uncarbureted fluids (recirculated burnt gas and/or air) fed into the combustion chamber through the manifolds. In the case of high loads, the two manifolds are supplied with fuel so as to obtain a homogeneous mixture with a fuel/air ratio close to 1 in the combustion chamber.
In any case, the engine performance capacities cannot be used at their maximum and the mixture fed into the combustion chamber does not allow engine knock risks to be limited. Furthermore, in case of fuel mixture and uncarbureted fluid stratification as mentioned above for average loads, filling of the combustion chamber is poor considering that only part of this chamber is occupied by a fuel mixture. Moreover, for low or high loads, the fuel mixture fed into the chamber is a homogeneous mixture with a fuel/air ratio close to 1. Such a fuel/air ratio is favourable to local self-ignition (engine knock) considering the location of part of the fuel mixture at a distance from the spark plug and consequently at a distance from the ignition initiation of this fuel mixture.
The present invention aims to overcome the aforementioned drawbacks by means of an internal-combustion engine control method allowing to use the entire potential of the engine while avoiding creating zones in the combustion chamber favouring engine knock.